This is a typical integration problem. For integrating, mediating, proxying etc. different services and even transferring data, use Apache Camel. For a short answer what Camel is, see What exactly is Apache Camel?
In Camel you define routes using a Java DSL or a XML Spring DSL. Proxying a web service is described here. Using the XML Spring DSL, the route would look as follows:
<route>
<from uri="jetty:http://0.0.0.0:8080/myapp?matchOnUriPrefix=true"/>
<to uri="jetty:http://realserverhostname:8090/myapp?bridgeEndpoint=true&throwExceptionOnFailure=false"/>
</route>
Using the Java DSL, this would become:
from("jetty:http://0.0.0.0:8080/myapp?matchOnUriPrefix=true"
.to("jetty:http://realserverhostname:8090/myapp?bridgeEndpoint=true&throwExceptionOnFailure=false")
There are many different protocols that are supported by Camel such as JSM, SOAP WS, RESTful WS, plain HTTP, TCP. Have a look at https://camel.apache.org/components.html for all possibilities.
The next example shows you how easy it is to define a RESTful server using the Restlet component:
from("restlet:http://localhost:8400/orders/{id}?restletMethod=post")
.process(new Processor() {
@Override
public void process(final Exchange exchange) throws Exception {
final String res = "received [" + exchange.getIn().getBody(String.class) + "] with order id = " + exchange.getIn().getHeader("id");
exchange.getIn().setBody(res);
}
});
The corresponding client looks as follows:
from("direct:start")
.setBody(constant("Hello, world!!"))
.to("http://localhost:8400/orders/22?restletMethod=post")
.log("order: direct start body result = ${bodyAs(String)}")
That said, Camel supports a plentitude of enterprise integration patterns such as splitter, aggregator etc. that can be used for your needs. Have a look at http://camel.apache.org/enterprise-integration-patterns.html for more information about that.
You can just use "normal" Java classes for transforming data and hook them into the routes. Beside that there are many integrated type converter for transforming one data type to another. These converters can easily be extended. See https://camel.apache.org/type-converter.html.
You could use Camel as your base integration framework and add e.g. JMS/ActiveMQ for the communication. However, it is also possible to use ActiveMQ as your base and add Camel for transforming the data, see https://activemq.apache.org/broker-camel-component.html: "The broker camel component makes this even easier - which intercepts messages as they move through the broker itself, allowing them to be modified and manipulated before they are persisted to the message store or delivered to end consumers." However, I prefer to use Camel as the base and add JMS/ActiveMQ for the asynchronous communication (e.g. if message persistence is needed or if the communication has to occur between different hosts).
Camel supports a huge amount of different protocols and formats. However, you don't have to use them, if you don't need them. Just add the dependencies to your pom.xml if you need them. Apache Camel is a small library (11.2 MB) with minimal dependencies for easy embedding in any Java application. Camel runs standalone, in a Servlet engine, or in an OSGI container such as Karaf/ServiceMix/JBoss Fuse ESB. You can start small and the application can grow, if your needs are growing.
For starting using Camel, read the excellent book by Claus Ibsen: http://www.manning.com/ibsen/.
